Process for the production of aluminium silicosulphide



f Patented Aug. 3 Q

I I PROCESS'FOR THE PRODUCTION OF" 1 SILICOSULPIEDE1 Oskar Schob'er and August 'Sclmitzspahn, Horv rem, near (lologne on-the-Rhine, Germany, assignors to American LurgiCorporation, New York, N. Y., a Corporation of New York- 7N0 Drawing. Application June so, 1932, Serial i No. 620,306, and=in Germany March 30,1931

9 Claims. (01. 23 134) This invention relates to aprocess for the pro-- duction of aluminium silicosulphide. The sulphides of aluminium and silicon, which could be usefully employed, for example, in vul- 5 canizing rubber, are produced in knownmanner,

by treating powdered aluminium or amorphous silicon with-sulphur at-elevated temperature. The preparation of pulverulent silicon, however, is'expensive, as is also the reduction of, alumin- 10 ium to powdenin addition to which, in the latter case there is the known heavy risk of vexplosions in the pulverizing plant. Moreover, the

reaction between aluminium' and' sulphur ,pro-

, ceeds with such violence "that-losses of material are hardly avoidable. For these reasons, t here-' fore,,none of theaforesaid sulphideshas, sofar,

found practical 'application,- notwithstanding their saidsuitability for vulcanizing rubber. I

It has now been ascertained in accordance with the present invention that they aforesaid inconveniences attending the production of the individual sulphides of aluminiumand silicon can-be obviated byproducing their mixed sulphides jointly by'treating with'sulphur originating materials which contain both aluminium and silicon; This procedure afiords, in the first place, the advantage that the originatingmaterials may consist of' aluminium-silicon alloys, which can be produced; for exampleby the their-- malreduction of raw materials containing alu;

mina and silica, at considerably lower, costthan,

each of the] components separately Said'orig inating alloys are available with particular advantage andfa't specially low prices, inthe form of liquationfiresidues, comparatively high in silicon, obtained as {a by product in the conversion of the aluminium-silicon alloys-especially those highinsilicon -obtained in the thermal reduction of 'aluminous"andsiliceous raw mate rials, into alloys that are lower in silicon, by

liquation. 1 The employment'fof suchfalloys affords the further advantage that these alloys are extremely brittle and can therefore be pulverized to any desired degree'of fineness at low cost and, above all, without risk of explosion. This is additionally"facilitated by the fact that, when, alloys obtained as by-products from liqua tion processes are employed, they'already exist in a, form which renders further pulverization easy; In' general,- such 'liquation products, containing forexample about 35-40% of metallic A1 and about 40-50% of metallic Si as they come from the liquation process,*can be employed" direct forlthe production of the, mixed sulphidesgacsuch as chamotteat onlya single point. This ithroughoutthe entire mass, by reason of the able workingiconditions, in order to ensure that Employing the reaction components a sufiicording to the present invention. Their composition may, however, be modified in anydesired manner, by'the addition of aluminium or silicon, or of an alloy higher in aluminium or silicon, prior to the action of the sulphur. V r 0 A further substantial advantage ofthe process of the present invention resides in the circumstance that the presence of the silicon moderates the energy 10f the reaction of the aluminium with the sulphur, the aforesaid unduly violent reaction phenomena otherwise attending that reaction being prevented? The components may also be employed, either wholly or in part, in the form of a mechanical admixture instead of in the form of an alloy. In this'case also, the advantage isrobtai'ned that thereaction withthe sulphur'can be performed in a singlev working operation, and that 'saidreaction proceeds with less violence than'that of pure aluminium with'sulphur, the losses attending this latter reaction being consequently prevented; 5

In carrying out the process of the present invention, the, for example, finely pulverized aluminium-silicon alloy, or finelypowdered mixture of aluminium and silicon, is well mixed with sulphur-.-for example, in the form of flowers of sulphurand the mixture is' then brought into reaction by'raising the temperature. Since the reaction is highly exothermic,-it usually Suficient to heat'the reaction mixture-placed, for example, ina crucible or other reaction chamber bounded, for example, by refractory material may be effected by means, for example, era

red-hotiron rod, a primer of. the kind used in alumino-jthermic reactions, or in any other way. Thereactionihaving 'thus been initiated in one portionof the mixture, it -;will then propagate heat generated by the process itself. 7

It has been'ascertained that special advantagesare obtained by carrying out thesaid reaction in a molten state, i. e. by employing suitthe exces's of the heat of the reaction per unit of time, plus any externally applied heatpover the heat losses, due to conduction and radiation, inithe same period, is? sufficient to bring the mass into a state of 'fusion'and maintain itin that state throughout the reaction. 1 V

' 1 The following typical measures may be menti oned as suitable-for the attainment fof object:

ciently fine state of division. In general, it is' advisable, for example, thatthe metallic components in particularsuch as siliceous residues from the liquation of aluminium,siliccn alloys .ance with theproeess of the present invention,

should'bef .firie 'enough to pass] through asieve ,withno t less than" 3,600 meshes per"sd."'cm1,

for example one with about 10,000,1ne'shes per a a a v canizing rubber, destroying pests, removing hair from' the skins of animals, cosmetic purposes,

sq. cm. l

Avoiding anyconsiderable--e. g. over excess of sulphur by comparisonwith the thBO-"Q- retical amount according to theequations:71.'

It is preferable to employ the sulphur in amounts approximating to these equations. Nevertheless amounts which .arefboth smaller 1 and larger than the stoichioinetl'ic' amounts-01fv sulphur may be employed. 1

In operating without external application of a heat and solely. by; initiating; the conversion rapid application of considerable-quantities of external heat,to accelerate the propagation of the, ;reactionthroughout the whole mass.

It has also been f ound desirable that the amounts of reaction mixture employed should not: be too small, and that their spatial-dispose tiongshould be such; as to iacilitate as faras possible the retention ofrthe heat and theyrapid propagation of the reaction; that is to say, preferablywith a small surface of the mass in re lation toits height.

1 Itis important that the aforesaid ignition effectedirom above-$01; example, in a crucible filled, with the reaction mixture-should take place as uniformly as possible over the entire cross-sectional area ofthe mass," under which conditionsthe "reaction Willproceed, in a strati fied mannen; irom above downwards, overthe whole' cross section oi the crucible.- 1

lior the purposeof. reducing the heat losses, the-crucible or other reaction apparatus may be provided with; ayheat-insulating shell.

; Fresh quantities -of the reaction mixture} in briquette form if desired, may be introduced into the wholly [or paru uy molten mass, i i the same manner, for example,las'practised in theski-called aluminothermie, process or; the like. I v

7 ,Whentheconversion is completed,

ing molten product may, if desired, be pgured mtg uld t Tljhe molten products obtained inaccordancewith the present invention are distiiiguished, in comparisongwith those obtained when. the reaction mixture is' not {used during the conversion process, by theirrcqnsiderablyhigher conter t of sulphide-sulphur decomposable bywater with liberation o f sulphuretted .hydlQgcn. Product s. obtained frqm -liquation residues for example with about eto %fof metallic Si and 35;to

40% of metallic Al, treated according to'th eg P s inveni on fu n sh; 91, e amp e 5r5 finishing: 128 for Al and 322 grms. of

(or more) of their weight of sulphuretted hydrogen Q 'IIhe, mixed sulphides, especially those produced in the molten state, prepared in accordha vebeenfoundadmirably suitable for a great variety'of purposes, such as for example vulthepreparation oi luminous paints, andgfor furprecipitating sulphides for manufacturingand analytical purposes and the According to the purpose in view, the products obtained in the first place, in the form of a pulverulent, sintered or fused mass, may be reduced to asufiiciently fine condition, for example in enclosed ball mills, prior to being used.

For thepurpose of preparing mixed sulphides containing additional sulphides, the alloy or mixture of I aluminium and silicon employed. as

the originatinginaterial may, prior to the reaction with sulphur and,'if"desired,' duringhthe process of pulveriaation, be mixed with bther metals or with metallic compounds, preferably finely powderedvfurnishin'g sulphides on treat ment with "sulphur under the reaction conditions. The aluminium-silicon alloy employed may also, in'itself, already contain other metals or other constituents in addition to the said components. I

An advantage which is o f' particular importance inconnec'tion with many appli'cations of these products is that practically: their entire sulphur content can be" converted ito sulphuretted hydrogenby' mere 'treatme'ntwith water Without theaid of acids. I

. Example 1 I consequence of the resulting initiation of the conversion process, the .whole .mixture burns away, without, however, fusing. The scaly mass of aluminium ,silico-sulphide obtained'when'the reaction has terminated contains up to' 8% ormore byrweight ofsulphur,,and can be groundfor example in a ball mill-when cold.

r Example 2 A mixture or, 20 kgs'. of the liquation residues employed'in Example 1 (and of the same degree of fineness) with 32 kgs, of powdered'sulphur is placed'in a stout fireclaycrucible', insulated to prevent loss of heat, 70 cm; deep and 38 cm. Wide inside. A priming charge of 500 grms. of armixture composed of 1'78.grms..of powdered powered Si is spread over the said mixture.

Q Lfter igniting the priming charge with a match the conversion of the reactionmixture takes place .within about 20 minutes, the whole mass passing into a state of fusion. Y n

Directly the conversion is completed, the still fi em is Po d into s a emou s-b Th resulting product contains 4552% by weightof sulphur.

The term mixed sulphides? used in the foregoing description is intended to include in all cases products consisting essentially of aluminum and silicon in'chemical combination with sulphur, which products may additionally contain minor quantities of various substances such as iron, titanium, calcium, aluminum oxide, silicon carbide, silicic'acid, and the like; i

We claim:- i V 1. A process for the production of: products consisting essentially of the sulphides of aluminum and silicon which comprises causing metallic aluminium, together with metallic silicon, to react with sulphur at elevated temperature.

2. A process for the production of products consisting essentially'of the sulphides of aluminum and silicon which comprises causing metallic aluminium, in a finely divided state, together withmetallic silicon,- to react with sulphur-by heating the reaction mixture to reaction temperature at one point at least.

3. A process for the production of products consisting essentially of the sulphides of aluminum and silicon which comprises causing metallic aluminium, in a finely divided state, together with metallic silicon, to react with sulphur by heating the reaction mixture to reaction temperature at one point at least, by burning an igniting charge. i I

4. A process for the production of products consisting essentially of the sulphides of aluminum and silicon which comprises causing a mixture of an alloy of aluminium with silicon in a finely pulverized form, to react with sulphur at elevated temperature.

5. A process for the production of products consisting essentially of the sulphides of aluminum and silicon which comprises causing a mixture of metallic aluminium, metallic silicon and sulphur to react at elevated temperature.

6. A process for the production of products consisting essentially of the sulphides of aluminum and silicon which comprises causing metallic aluminium, together with metallic silicon, to react with sulphur," in a molten state.

7. A process for the production of products consisting essentially of the sulphides ofaluminum and silicon which comprises causing a mixture of a finely powdered aluminum-silicon alloy, obtained by liquating an aluminum-silicon alloy containing a lower silicon content than that of the 'liquation product, to react with sulphur in a molten state; I I r 8. A process for the production of products consisting essentially of the sulphides of aluminum and silicon which comprises causing a mixture of, sulphur and a finely powdered aluminum-silicon alloy, obtained by liquating an aluminum-silicon alloy containing a lower silicon content than that of the liquation product, to react in a molten state by heating said mixture at one point by means of an energetic ignition charge.

9. As'an article of commerce, a product consisting essentially of sulphides of aluminum and silicon.

OSKAR SCHOBER. AUGUST SCHNITZSPAHN. 

